1. Field of the Invention
The invention generally relates to electronic gaging systems. More specifically, the invention concerns in-process gaging apparatus for use with numerically controlled machine tools with wireless transmission or telemetering of the gaging data to a computer-controlled receiving unit.
2. Description of the Prior Art
In order to perform in-process dimensional gaging of workpieces being machined by a numerically controlled (NC) machine tool, it is necessary to employ some type of wireless transmission of gaging information from a gaging unit to a receiving unit. This necessity is due to the fact that the gaging unit must be configured for retention in the NC machine tool magazine similar to the actual cutting tools retained therein. Additionally, such a gage unit must be automatically selectable by the NC tool changing program. Hence hard wired coupling of the gage unit's output to a receiver and display unit is obviously not feasible.
One prior art approach to in-process gaging at an NC machining center is disclosed in U.S. Pat. No. 4,118,871--Kirkham, wherein a radio frequency signal is substantially attenuated by a gage probe's contact with workpiece and reference surfaces to indicate indirectly the spindle position of the numerically-controlled machine tool. This indirect method relies on the accuracy of the NC machine tool movement and no direct telemetering of measurement data from a gaging transducer is employed. Additionally, the radio frequency signal employed is susceptible to electromagnetic interference and must be used within a relatively short transmission distance between the gage head and a receiver.
Another prior approach, that of telemetering actual gage transducer measurement data via an antenna-coupled radio frequency signal, is taught in U.S. Pat. No. 3,670,243--Fougere et al. and U.S. Pat. No. 4,130,941--Amsbury. The above mentioned interference problem is not solved by this approach.